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Tick guideAmerican Dog Tick (Wood Tick): How to Identify It and What It Spreads
The American dog tick is one of the most common ticks people find on themselves and their pets east of the Rockies. It does not spread Lyme disease, but it can spread Rocky Mountain spotted fever and tularemia.
Quick answer
The American dog tick (Dermacentor variabilis), often called a wood tick, is a reddish-brown tick about 1/4 inch long with white or cream markings on its back. CDC says it is widespread east of the Rocky Mountains, bites mostly in spring and summer, and can spread Rocky Mountain spotted fever and tularemia. It cannot spread Lyme disease.
CDC lists the American dog tick among the ticks that cannot transmit Lyme disease bacteria. It can spread other infections: CDC names tularemia and Rocky Mountain spotted fever. CDC says adult females are the stage most likely to bite people, and bite risk is highest in spring and summer.
What it looks like
Most people notice the adults, which are much larger than deer ticks. The University of Maine Tick Lab and the Connecticut Agricultural Experiment Station describe them like this:
- Adult female: about 1/4 inch unfed. Reddish-brown with a cream-white shield just behind the head. After feeding she can swell to 1/2 inch or more and look like a dark pinto bean.
- Adult male: slightly smaller, reddish-brown with cream or gray markings over most of the back. Males stay about the same size when they feed.
- Nymphs and larvae: much smaller. They feed mainly on wild animals: larvae on mice and voles, nymphs on animals such as raccoons and opossums.
Why is it called a wood tick?
“Wood tick” is a common nickname. The Minnesota Department of Health, for example, calls the American dog tick the wood tick. The name can be confusing because a different species in the Mountain West is named the Rocky Mountain wood tick. The two look alike and belong to the same genus, Dermacentor.
Dog tick vs deer tick
This matters because deer ticks spread Lyme disease and dog ticks do not.
| American dog tick | Blacklegged (deer) tick | |
|---|---|---|
| Adult size (unfed) | About 1/4 inch | Under 1/8 inch |
| Back | Reddish-brown with white or cream markings | Plain dark shield; female body red-orange |
| Adults most active | About April to August | Spring and fall |
| Spreads Lyme disease? | No | Yes |
The Minnesota Department of Health notes the deer tick is much smaller than the American dog tick, and the reddish-orange back of the adult female deer tick is a helpful clue. More detail is on our blacklegged tick page.
Where it lives
CDC says the American dog tick is widespread east of the Rocky Mountains, with limited areas to the west. CDC also notes that a newly described close relative, Dermacentor similis, lives west of the Rockies, and that more research is needed on how both species spread disease.
The dog tick handles drier conditions well. The University of Maine says it lives in open fields and lawns as well as forests. The Connecticut Agricultural Experiment Station finds it most often along roadsides, paths, trails, marshy areas and meadows with tall grass or weeds. See where ticks live for more.
When it is active
Adults come out in spring. In New England, the University of Maine reports adults mostly from April through August, peaking in May and June, and inactive by October and November. The Connecticut Agricultural Experiment Station describes a similar season, from mid-April or early May until August.
That timing is one more clue: a large tick with white markings in June is more likely a dog tick, while a tiny dark tick in late October is more likely a deer tick.
Diseases it can spread
- Rocky Mountain spotted fever. The University of Maine calls the American dog tick the main carrier in the eastern U.S. CDC says RMSF can be deadly if not treated early, and that clinicians should start treatment when they suspect it, without waiting for test results.
- Tularemia, a bacterial infection CDC also lists for this tick.
Not Lyme. The University of Maine notes that dog ticks can pick up the Lyme bacteria but apparently cannot pass them on, and CDC confirms they cannot transmit Lyme disease. See our co-infections hub for other tick infections.
Tick paralysis
Some Dermacentor ticks, including this one, can cause tick paralysis, which comes from a toxin rather than an infection. The Connecticut Agricultural Experiment Station describes weakness and poor coordination that start in the limbs and can move up to the face and breathing. Removing the tick usually reverses it, and recovery is usually complete. It says most cases are linked to the Rocky Mountain wood tick, though the American dog tick has also caused it. The University of Maine lists tick paralysis in dogs as well.
If an American dog tick bites you
Remove it right away with fine-tipped tweezers, pulling straight up. Our tick bite guide covers how, and the first 72 hours after a tick bite explains what to note and what to watch for.
Get medical care promptly if you develop fever, headache, rash, nausea, vomiting or muscle pain in the days to weeks after a tick bite, and mention the bite. CDC lists these as early signs of Rocky Mountain spotted fever. Seek emergency care for weakness that is spreading or trouble breathing, and check the whole body carefully for an attached tick.
Prevention
Because dog ticks favor grassy edges and paths, check yourself and your pets after walks through fields and along trails. Practical guides:
- Tick bite prevention basics
- Tick-proof your yard and hiking and ticks
- Protecting your dog from ticks
Prevention is step one of our plan to beat Lyme together.
We are collecting real experiences about telling dog ticks and deer ticks apart from people who have lived it, shared with their permission. As stories come in, they will appear here, clearly marked as personal experience rather than medical advice.
At a glance
| Scientific name | Dermacentor variabilis |
|---|---|
| Other names | Dog tick, wood tick |
| Size | Adult about 1/4 inch unfed; fed female 1/2 inch or more |
| Key marks | Reddish-brown with white or cream markings |
| Range | East of the Rocky Mountains, limited areas west |
| Peak bite risk | Spring and summer |
| Spreads Lyme? | No (per CDC) |
| Linked to | Rocky Mountain spotted fever, tularemia, tick paralysis |
See which ticks carry Lyme disease, compare the lone star tick, or browse all types of ticks.
Frequently asked questions
Can an American dog tick give you Lyme disease?
No. CDC lists the American dog tick among ticks that cannot transmit Lyme disease bacteria. It can spread Rocky Mountain spotted fever and tularemia.
Is a wood tick the same as a dog tick?
Often, yes. Many people, including the Minnesota Department of Health, call the American dog tick a wood tick. A separate western species is named the Rocky Mountain wood tick.
How do I tell a dog tick from a deer tick?
Dog ticks are bigger (about 1/4 inch) and have white or cream markings on a reddish-brown back. Deer ticks are under 1/8 inch with a plain dark shield and dark legs.
When are dog ticks most active?
In spring and summer. In New England, adults are mostly active from April through August, peaking in May and June.